Hey there, Paul. You know where I'm at so it will be no surprise to you that my feedback will not be on a scriptural basis. Lots of scriptural experts on this board to draw from, just not me.
Completely different dynamic but my mother was determined to run my life, too. I loved her dearly but she was manipulative and controlling. I fled from her when I was 19, moved a thousand miles away to attend university and then for the rest of her life lived at a distance. I visited my parents frequently, often with my own family in tow, and sometimes during my visits she would ask when I was going to "move home", in between times when she tried to interfere with my life. (Some of those times were when she went ballistic over either my involvement or my wife's involvement in the WTBTS. She was right those times but all the other crap that went down made me stubborn and defiant and I said some things to her I now regret.) My dad asked once if I'd ever move back and I told him frankly that I would like to but for my mother's meddling. He just nodded. I moved back to my home town the year after she died. I wish it wasn't that way but in the end she and I succeeded in diminishing our relationship and took away years and years of being with her, my father and my sibs (all of whom complained about her meddling but who, unlike me, put up with it and stuck around).
Some of what drives your mother is the Watchtower but most of it is because she is your mother. She gave birth to you, changed your diapers, fed you, bathed you, dressed you, comforted you, protected you and laid the foundation for the person you became. She feels a bond with you that is as deep as life itself. She will give you credit for some things but deep down she will believe she knows best what you need in life and that will never change. You will always be her child in her mind and heart.
In hindsight and with the benefit of almost six decades of experience and maturity I would do things differently, and I am certain it would have worked out if only because I had demonstrated my resolve. I would seek a true detente. I would offer to become a greater presense in her life on one condition, and that is if she would accept that I am who I am and the only result that would accrue from her attempts to alter that reality is distance between us, which neither of us wanted. I could be mistaken but I perceive that your challenge is much the same. Putting up with a 40 minute rant is a good indication of the love and respect you have for your mother but is not a good indication of your resolve to live your own life. Whether you and your mother know it or not, the stakes are high for both of you.